Propeller



June 3, 1941.

i G. F. BUCKINGHAM PROPELLER Fi ed Jan. 21, 1957 2 Sheets-Sheet 1 June 3, 1941. G. F.3BUCKINGHAM PROPELLER Filed Jan. 21, 1937 2 Sheets-Sheet 2 Patented June 3, 1941 UNITED STATES PATENT oFrlca' 1 311, George: Frederick Buckingham, Oakland, Calif. Application January 21, 1937, Serial No. 121,493

17 Claims.

.This invention relates to improvements in propellers, primarily, but not exclusively, those used inaircraft. v v v r In order that the objects of this. invention may be understood it is expedient and may be necessary, first to set forth certain theoretical assumptions and certain facts concerning the conditions afiecting the performance of a.blade of an aircraft propeller, inasmuch as these have influenced the structural features of the device.

The assumptions are: that elements of a blade may properly be regarded as contiguous airfoil sections, individually of infinitesimal span: that constant speed of rotation makes for engine emciency (best performance being secured at the design rate): that a blade element develops the best ratio of lift (thrust) to drag (torsional resistance) when it is set at a certain angle to a the direction of Yits movement: that when a propeller rotates at constant speed," with all its blade-elements set at the angle of- L/D max., the sum of the torsional resistances developed by the elements exactly equals the available engine power: that, when set for best efliciency,

the resistance developed by an element of fixed area varies as the square of its true velocity.

The facts to be noted are: that the speed of flight is imparted to every element of a propeller blade; that, while the engine continues to opcrate, a certain rotative speed is imparted to each element of a blade, diil'erent from that imparted to any other; that the two directions and the true velocities of the elements movements are the resultants of the common forward speed and of their individual rotative speeds; that any change in the speed of flight causes changes in the true direction of movement and in the true velocity of every element of a blade; that these changes are not uniform but are proportionally greater for elements 0! relatively low rotative speed; that the' settings of all-the elements of a blade are therefore required for full efllclency, to a be adjustable in different degree: that the effective "area ofa blade is required for full emciency to be capable of variation to compensate for the changes in the true velocities oi its elements, caused by changes in the speed of flight; that, when the differencebetween the flow and the "high speeds of flight is very pronounced, then, as the top of the range is approached, all the elements of ablade, but particularly those -of relatively low rotative speeds, exert the thrust forces which they develop in directions which tend to become less favorable for propulsive effect; that; at very high flying speeds, conditions prevail which'virtually nullify the useful effect of elements placed near the axis; that the changes which take place that the resistances developed by elements soplaced increase largely as their usefulness decreases.

The objects are: First, to provide means whereby each concentric part of the blade suriaces may automatically be caused to assume substantially the correct angular setting and also the proportional area conforming to the true direction and velocity of its movement at the prevailing forward speed; second, when the conditions at and near the top speed of the range are such that any part of a blade surface placed near the axis would be unable to add appreciably to the effective thrust and would develop greatly increased resistance, to provide means whereby the more eiiicient outer parts may be rotated while the effect of such inner parts is eliminated; third, when the conditions are such that the changes of area demanded are so large as tobe impracticable for blade parts within a radius which isgreater than that which limits the employment of the means for elimination,

to provide flexible members in the intermediate zone capable of transmitting rotative impulses and thrust forces, the settings of whoselnner and outer' ends maylbe differentially changed automatically in accordance with the angular changes demandedin order that resistance developed by these, parts may be kept as low as possible; fourth, to pr vide correlated automatic means, optionally'employable, adapted to maintain a selectable rate of engine. revolution.

These objects are integral to the purpose of the invention which is to secure substantially,

constant thrust,vat the rate of revolution chosen,

throughout the range of forward speeds; they arembtaihed by mechanism illustrated in the accompanying two sheets of drawings, in

which- Figure 1 is a perspective drawing of flexible members replacing certain, blade parts; Fig. 2 is a diagrammatic detail typical of certain rigid radially disposed rotating members; Fig. 3 13a perspective view showing the general disposition of means wherebychanges of theangular settings of concentric blade parts and variations the line 88 of Fig. 9; Fig. 9 is a plan partly in section of parts employed in the application and control of the forces by which requisite changes are effected in blade parts; Fig. 10 is a section on the line Illlli of Fig. 9; Fig, 11 is a section on the line ll--II of Fig. 9; Fig. 12 is a perspective view of a construction by which the more efllcient outer parts of blade surfaces may be rotated when the effect of certain inner parts is eliminated, means for throttle control also being shown; Fig. 13 is a dislots are placed at intervals corresponding 'to the spacing of the controlled element-forms.

The ends of the node pins are. engaged in straight slots in the element-forms. In a typical element form the node pin also passes through holes in the yoke and any movement of the rod along the bore in the mast thus causes different changes of angular settings for all the controlled elements and also changes the area pf the blade.

The heels of masts are secured to the web of a channel ring 2', from whicheach mast extends radially outward.

Set firmly on mast I, in a position immediately next to and inside the rotatable circular flange of the base element II, is a collar shown as being made in one piece with 4 curved members extending radially from it. The outer ends of these curved members clear the inwardly re-" turned edge of the said flange and are made fast to a circular part of the frame i2. This radial-armed piece contributes to the rigidity agrammatic sectional view of a construction which the changes of flying speed unavoidably entail and should not include any element which at the highest speeds of the range would be required to set at an angle unfavorable to the effective application of any thrust force it might develop. I

Such a blade has a mast I, on which are pivotally mounted the positively controlled element-forms. Each typical element-form. includes, slidably fitting the mast I, a yoke l4, made with an arm on each side; slots are cut in these arms and pins, projecting from extensors ii, are movably engaged in the slots. Thus any movement of the yoke along the mast is caused to change the distancebetween the ends of extensors and to alter the area of the blade.

The innermost or base element-form II, has no extensors; it consists simply of a sleeve rotatably fitting the mast I, it is enlarged at its inner end into a circular flange of a diameter equal to the width of the base element.

The outermost or tip element-form I6, also has no extensors; it is a simple sleeve rotatably fitting the mast, made with supports for the tip shield I1. v 7

Wires I9, are firmly secured to the flange of the base element-form II, they pass through pipe-like'reinforcements 20, which are embeddedin the flexible, elastic covering 2| between the' element-forms.- The wires also pass through passages in. the ends of the extensors l5; they are carried around rollers mounted on springs which keep them taut and which are housed in thetip shield l'l. Y

A stop band 22, is fixed on the mast for each ,of .the mast ,l, and is called the cross stay I0 (see Figs. 3, 8, 9 and 10). Further support is given to the mast I, by the sleeve of the base element II; in the inwardly returned edge of the circular fian'ge of this base element ll, a groove is formed and balls or rollersare set therein engaging a complementary groove in the circular partof the frame I2. The frame I2, is made with parallelstraight members tangent to its circular part and these are set -transversely across the edges of the channel ring 2, to which they are fastened.

The transverse edges of the frame l2 are shaped sothat each makes one side of a straight race or runway for a series of balls (see Figs. 9 and 11). The other sides of these races are formed by stiffeners 29, attached .to a circular cowl 6, concentric with the ring 2. The front of the cowl 6, is turned inwardly so that the clear opening is less than its maximum diameter.

The heel sleeve 4, is rotatably fitted on the mast I, between the web of the channel ring 2 and the cross stay I0; its inner end is cut into a gear which meshes with the main rack 5, a member which is extended to pass through an opening in the front flange of the ring 2 and is firmly attached to the cowl 6.

The inner end of the innermost link of the rod is formed into a node 3, in which the master node pin 8 is fixed transversely; this pin passes through slots 9, cut longitudinally in the mast and also through slots I, cut diagonally in the heel sleeve 4. Any telescopic movement of the cowl 6, in relation to the ring 2, due to variations in the frontal air pressure on the cowl by the action of the rack 5 causes the heel sleeve i to turn on the mast I; the master node pin element-form to prevent its outward movement- I Placed within the mast l, is a rod composed of separate links, connected in such a manner that they may be turned, readily through different angles; each link is made with a node 3, which slidably fits the bore inthe mast. In each node a pinis fixed transversely to the link; the. node pins pass through differently curved slots cut in the mast; the nod s and the 8 is then forced along the slots 9, by the sides of the diagonal slides I; thus the entire articulated rod is moved within the mast with the effects noted above.

-.The runways or races for the series of balls are partially obstructed by switch points 30 (see Figs. 3, 9 and 11), fixed firmly at the rear flange of the channel ring 2, so that as the cowl comes equivalent to the frontal air pressure on the cowl. Each series of balls-has a threaded adjuster pin 32; a locking bolt 33 is held jbya spring in close engagement with that particular one of a plurality of longitudinal chases, cut to the base of the thread, which maintains the adiustment desired.

' typical element-forms, the ends of the master node pin 8 are extended and set into a collar, it, which movably encircles the heel sleeve'l. This collar 23 is provided with racks 24 meshing with are gears 28, 26 and 21, which cause the forces developed by adjustable counterweights 28, substantially to equalize those developed by the rod parts. I

Highest emciency is obtained when the means for eflecting rotation of the ring 2 donot rotate with it.

Firmly secured at intervals to the inner surface of the ring 2. but of a slightly smaller dijecting from racks in mesh with are gears attached to the inner ends of the flexible connect- .i'ng members, causing these inner ends to assume substantially the correct angular setting required at all stages of the speed range.

Due to the manipulation of flying controls the demand on the engine for power varies constahtly; acceleration or deceleration of the normal rate of rotation must ensue unless the throttle is adjusted instantly. To meet this situation, the engine'shaft 5|, (see Figs 12 and 13), is made with a splined portion 55, on which is slidably fltted the inner race of a ball bearing El, from which project fingers Bl, having ameter, there is a circular gear M, meshing with gears M), which are set on radial auxiliary shafts t9, driven by bevel gears (not shown); the master bevel gear being fixed on the engine shaft.

Brackets 50, secured to the frame of the engine, house the bearings for these auxiliary shatts and also carry pins on which are mounted the thrust wheels 5|. An annular member 52 collects excess lubricating oil thrown off from the ring 2; it is returned to the pump through a pipe 53. a

In cases where high rotative rates make it impracticable to employ a circular gear M, of a diameter approximately as large as that required for the ring 2; an inner ring 42. (see Figs 1, f1, 5, 6, land 13) of a reduced diameter becomes necessary and connecting members are introduced between the ring 2 and the inner I ring H.

The resistance of these connecting members is reduced to a minimum when they are streamlined in form and when the different adjustments required for their outer and inner ends are accurately made at every stage of the speed range.

These connecting member are adjustable for tension by threaded sleeves 3|, set in sockets formed in the channel ring 2 An arc gear (see Fig. l) is mounted on a rigid member 81, close 'to its outer end. in mesh with the gear of the heel sleeve 4. This .rigid member passes through the web of the ring 2 extending radiallyto the inner ring 42, in whichis provided a bearing for its inner end.

A gear SI, flxed at its outer end, by racks, moves hooplike members 3! placed in the ring 2. These hoops are provided with racks 4| which mesh with are gears 4| fixed on the outer ends of the flexible connecting members; so that, whenever the heel sleeve 4 is turned by the pins which are engaged in slots in a collar 5d encircling the shaft 54 and rotated thereon by the action of gears 59, attached to rigid radially extending members 31. A turning movement is given to these members whenever there is relative telescopic motion between the cowl t, and the ring it, by means similar to those previously described. The outer race of the ball hearing 5%. is restricted to a store and aft'movement by a.- rack bi, attached to it, which sets between brackets tit, the latter fixed to the frame of the engine: a bell crank t2 having an arc gear meshing with the rack ti, actuates linkage connected with the throttle valve lever of the engine. This linkage includes, swinging on a fixed The pilot is thus enabled to select a position action of the main rack 5 responding to variment through the air is substantially main-' tained. Next to its inner bearing, the rigid radial member 31 has an attached gear 43, meshing with racks cut in the edges oi members 44,

. and encirclingthe inner ring. Any turn of the rigid member 31 thus causes the encircling members A4 to move on the inner ring 42. Slots cut in the members 44 actuate engaged pins proof the clamp 9, which sets the engine throttle V 'for theft. P. Mfrequired. It is possible for him to place the clamp in such a position that the variations of power demand are met automatically to the extent required. In Fig. 14, the automatic control is shown placed at its inoperative position, the movable pivot 61 'is'set in line with the fixed pivot 63, and there is no interieren'ce with the manual or other method of throttle control relied uponat. such times.

The precise means to be employed in a given case must necessarily take into consideration the medium in which the construction is to operate, the speed range, and the R. P. M; thus the scope or the invention cannot be restricted to any specific embodiment.

I claim and vdesire 'to Patent:

' 1. In a propeller blade, a flexible cover; a supporting mast placed longitudinally within the flexible cover; frames for concentric blade secprotect by Letters .wtions pivotally mounted on the mast; means adapted to hold each frame toa predetermined angle of attack with reference to the true direction of its movement, this movement being at all times and for each frame the resultant of the forward movement commonto allsectionframes and of the rotative movement of each individual frame; automatic means which simultaneously actuate the holding means to change the angular settings of the difierent concentric section frames in different degree as demanded immediately changes occur in the resultant directions of the movements of the frames in order substantially-to maintain ,the designated angle of attack with reference to. the true direction of its movement in each and every concentric blade part to the end that each may function efliciently as an-airfoil section at all cause movement of the rod longitudinally within the mast; frames for concentric blade sections set pivotally on the mast,-each frame engaging the protruding ends of one of the said pins and thus being held at all times to an angular set ting determined by the position of the rod within the mast; a flexible cover for the'assembled blade.

3. In a propeller construction. a ring; a tubular blade mast attached to and extending outward radially from the ring; frames for concentric blade elements pivotally mounted onthe mast; a vflexible cover incasing the blade; a jointed rod in the tubular mast; nodes -on each link or piece of the rod slidably fitting the bore in the mast; transverse holding pins secured in the nodes, each adjustably holding a. blade element frame at a given instant to a definite angular setting; slots of appropriate curvature, in the mast, adapted to change the angular settings of blade element frames in predetermined,

definite degrees by actuating changes in thetransverse holding-pins which pass through the slots and are movable in them, a master node I pin fixed transversely in the node on the in-.

nermost link; longitudinal slots in the mast commencing near the heel or butt of the mast through which the master node pin passes; a sleeve moveably' encircling the heel of the mast; sloping cuts in the heel sleeve through which the master node pin passes and is moveable; a gear on the heel sleeve; a cowl in telescopic connection with the ring; a rack attached to V the cowl in mesh with the heel sleeve gear, 4., sothat any change of position of the cowl in relation to the ring causes the heel sleeve to turn on the mast and thus the master node pin is actuated to move the entire rod longitudinally within the mast, whereupon the transverse holding pins are caused to effect differential changes in the angular settings of the concentric blade element frames.

4; In a propeller blade an elastic cover; a supporting mast placed longitudinally within the elastic cover; frames for concentric blade sections mounted on the mast; means comprising extensors housed in the frames; means adapted to hold the extensors to that degree of extension which gives to each concentric part of the blade the area substantially in the correct proportion to the true prevailing speed of its movement, this speed being the resultant of the forward speed and of its own speed of rotation; automatic means which actuate the holding means to change the degrees to which extensors are extended, immediately any change occurs in the true resultant speeds of concentric blade sections in order that concentric blade areas may be maintained in substantially accurate proportional relation to their true speeds.

5. The combination in a propeller blade of a mast fixed radially with respect to the axis of rotation; frames for concentric, blade sections mounted on the mast; extensors comprising members housed in and guided by the frames;

' means by which these. extensors are caused to vary the chord length of controlled sections; an elastic cover for the assembled blade.

5 6. The combination in a propeller blade of a radial mast; concentric frames pivotally mounted thereon; extensors housed and guided in the frames; means for effecting difierential changes in the angular settlngsof the frames;

means whereby the extensors may be caused to change the effective chord lengths of sections, thus changing the creams. flexible, elastic cover forthe assembled blade. '7. In a propeller blade a flexible, elastic cover: a supporting mast longitudinally placed within the cover; frames for concentric blade sections pivotally' mounted on the mast: members comprising'extensors, housed in the frames, capable of extending the minimum chord of blade sections; means for holding each frame to a predetermined angle of attack with reference to the true direction of its movement, which is the resultant of the prevailing forward movement and of its own movement of rotation; means for holding the extendible members to certain designed degrees of extension so that at a given instantv each concentric area of the blade is caused to be in a definite designed proportional relation to the true speed of its movement, which is the resultant of the forward speed and of its own rotativespeed; automatic means which simultaneously and immediately actuate the respective holding members to change difl'erentially the angular settings and to'change the chords] dimensions of concentric parts of'the blade so that the designed angle of attack may be maintained in spite of changes which occur in the resultant directions and so that the blade area may be adjusted to conform 40 to the changes which take place simultaneously in the resultant speeds; of the movements of the concentric parts of the blade to theend that substantially constant thrust may be developed from a constant rate of rotation.

r' 8. In a propeller construction the combination of flexible, elastic blade surfaces; frames for certain blade sections to be positively controlled; said frames pivotally mounted on masts extending outward radially from a ring to which the heels of the masts are secured; a concentric --cowl movable telescopically in relation to the ring; means adapted to develop, and to apply to the cowl, forces at all times equal and opposite to the force of the air pressure exerted on its frontal surfaces, due' to the motion of translation; means whereby changes in the relative disposition of the concentric ring and cowl brought about by the interaction of the forces affecting the cowl,, are caused not only to actuate means whereby differential changes in the angular settings of the said pivot-ally mounted frames are effected but also to actuate other means whereby differential changes are effected in the area of'concentric parts of the blades surfaces; means for rotating the ring to which v the blade masts are fastened.

9. In a propeller construction, a ring; blades extending outwards radially from the ring; flexible, elastic covers for the blades; a supporting 7 mast for'eachblade placed longitudinally within its flexible, elastic cover; frames for concentric blade sections pivotally mounted on the mast; members housed in the frames adapted to alter the chordal dimensions of blade sections; adjustable means for' holding each frame to a predetermined angle of attack with reference to the true direction of its movement which, at a given instant, is the resultant of the forward movement and of its own movement of rotation? adjustable means for holding the extendible members to such degrees of extension as to ensure for each concentric part of a blade that area which at a given instant shall have a designed proportional relation to the true speed of the parts movement, which is the resultant of 'the prevailing forward. speed and of its own.

rotative speed; automatic means adapted to actuate the respective holding means simultaneously in such a manner as to effect the adjustments of angular setting and of area required by concentric parts of' the blades immediately any change occurs in the resultant directions and in the resultant speeds of their movements; a ring gear attached to the blade-supporting ring; gears meshing with the ring-gear; radial auxiliary shafts, to the outer ends of which said meshing gears are attached; bevel gears ata master bevel gear in mesh with said bevel gears; axially disposed in relation to the ring gear, a drive shaft to which the master bevel gear is attached; thrust wheels in contact with the blade supporting ring adapted to receive the thrust force developed by the blades when the ring is rotated; pins on which the thrust wheels revolve; brackets attached to the engine frame or to some rigid part of the craft, holding the pins.

10. In a propeller construction a ring; means for rotating the ring; masts attached to and extending outward radially from the ring; frames for concentric blade sections pivotally mounted on the masm; members comprising extensors, housed in the frames, adapted to alter the chordal dimensions of blade sections; a sleeve turnable on the mast having a circular flange at its inner end of a diametersuiiicient to accommodate the base section of the blade; wires attached to the circular flange passing through slots in the pivotally mounted frames and through holes near the ends of extensors; a tip shield for the outermost element of the blade; rollers mounted on springs, housed in the tip shield, adapted to maintain effective tension inthe wires; means for changing the'angular settings of frames: means for changing the protrusion of extensors from their housings; flexible, elastic surfaces completely covering frames, extensors and wires.

11. In a propeller'blade construction, a ring; a mast extending radially outward from the ring to which its heel or butt is firmly secured; frames for controlled blade sections pivotally mounted'on the mast; a flexible, elastic covering for the blade; the base blade section frame being formed with a sleeve turnably encircling the mast; the inner end of the sleeve being enlarged into a circular flange of a diameter approximating the chord of the base section; a groove being formed in the edge of the circular flange; balls or rollers being placed in the groove; a complementary'grooved circular part being fixed to the ring to contribute further to the rigidity of the mast; a-collar made with radially extending arms being flxed on-the mast immediately next circular flange of the base section frame, the arms being curved inwardly so that they pass inside the grooved flange without interference .and are-firmly secured to the complementary to; andinside the rotatable circular part which is fixed to the ring. this part being made wider (or deeper) than the edge of the flange for this purpose.

'12. In apropeller construction, a ring; means for causing the ringto rotate; tubular blade masts attached to the ring and extending radially therefrom; frames for certain positively controlled concentric blade sections pivotally mounted on the masts; rigging wires strung between the frames; pipe-like reinforcements through which the wires pass; flexible, elastic ,surfacesenclosing the masts, the rigging tached to the inner ends of said radial shafts;

wires, the reinforcements and the frames;

Within each mast an articulated rod; means whereby the rod is caused to move longitudinally within the mast; means actuated by said longitudinal movement of the rod causing changes in the angular settings of the controlled section frames; means also actuated by said longitudinal movement of the rod causing changes in the effective chord-lengths of the concentric blade sections, thus changing the blade area;

adjustable means for counterbalancing centrifugal forces developed by the articulated rod and by those movable parts which are directly affected by its movements; means for locking and thus maintaining such adjustments; 9. cowl in telescopic connection with" the ring;

cause the longitudinal movement of the rod within the mast; adjustable means capably opposing pressure on the cowl due to the motion of translation; means for locking and thus ensuring the maintenance of such adjustments.

13. In a propeller construction a ring; attached to the ring a blade mast extendingradially outward; frames for controlled blade sections pivotally mounted on the mast; members comprising extensors housed in the frames; flexible, elastic surfaces completely enclosing the masts and theframes; means for controlling the angular settings of the concentric pivotally mounted frames; means for controlling the de grees to which the extensors protrude beyond their housings; a concentric inner ring; flexible members of stream lined form connecting the two rings; means for adjusting the tension of the flexible members which connect the rings; means for adjusting the angular settings of the outer ends of the said stream-lined flexible members; means for adjusting the angular settings of the inner ends of the said stream lined flexible members; means for rotating the inner ring; brackets set within the radius of the inner ring, secured to the engine frame or to a rigid part of the craft; pins rigidly attached to the brackets; thrust wheels mounted on the pins in contact with a suitably formed part of the inner ring, so that when the propeller is rotated the thrust forces developed by the blade are transmitted through the non-rotating brackets. to the engine frame or to some rigid part of the craft.

14. In the construction of a propeller blade, a mast; frames'for' controlled concentric blade sections pivotally mounted on the mast; separator bands fixed on the mast between the frames; continuous flexible elastic sufaces'completely incasing the assembled blade parts; means for controlling differentially the angular settings of individual frames; members comprisingextensors housed in certain of the frames; at jointed rod movable longitudinally within the .mast; a pin fixed transversely to each piece of means whereby changes in the relative positions of the ring and the cowl actuate the means which extensors, engaged in the diverging slots; a mas-' ter transverse pin for the innermost piece of the rod; a turnable sleeve encircling the heel of the mast; means for turning the heel sleeve on the mast; diagonal or sloping cuts on opposite sides of the heel sleeve adapted, when the heel sleeve is turned to actuate the master pin which passes through the cuts, thus moving the entire rod within the mast; a collar movably encircling the heel sleeve; holes in the heel sleeve collar in which the ends of the master pin are set; a rack fixed on the collar; a chain or meshing gears co-acting so that when the rack collar is moved lengthwise of the heel sleeve a threaded weight on' a lever arm is caused to move in the reverse direction; a lever arm threaded so that the position upon it of said weight may be adjusted; means for locking such adjustment so that it shall not be subject to disturbance when inaccessible during operation, but shall efiectively counterbalance the centrifugal forces developed 'by the rod and by the parts with which it is subjected movably connected, when the blade is to a rotary motion.

15. In a propeller construction, a ring; blade masts attached radially to the ring; blade sec-' tion frames mounted pivotally. on themasts; means adapted to effect definite changes in the angular settings of the frames; means adapted to elfect definite changes in the chord lengths of concentric blade sections, thus changing the I blades attached to the outer ring extending rabladearea; a flexible, elastic cover for each assembled blade; a cowl in telescopic connection with the ring; members rigidly attached transversely to the ring; stifieners on the cowl, so placed that each co-acts with a side of a rigid transverse member to form a race or runway;

a series 'of balls set in each runway adapted ated weights; radially disposed pockets attached to the ring adapted to receive balls as andwhen switched from the runways; means for rotating the ring so that centrifugal forces are developed by the balls in the pockets, which, acting through the balls remaining in the runways, capably oppose the pressure on the cowl resulting from any motion of translation; threaded sockets attached to the cowl; a port or opening in the side of each socket; threaded adjusting pieces screwable in the sockets, disposed in line with the centers of the balls in runways; longitudinal chases in the threaded adjusting pieces; bolts, housed. in the socket ports, each being normally held "in firm engagement with a selected longitudinal chase so as to prevent movement of its threaded ad justing piece in'its socket; springs to maintain the bolts in the locking position; so that adjustments regulating the weight of balls to be switched into the pockets may be made to meet anticipated conditions and positively maintained. 16. In a propeller construction, an outer ring;

dially outward; a concentric inner ring; flexible members of stream-lined sectional contour "capably connecting the outer and inner rings; a circular flange secured on the outer end of each flexible member; interiorly threaded sockets formed in' the outer ring; tubular threaded pieces adiustably set in the sockets, adapted to effect adjustments of the tension of the flexible meme bers inasmuch as the flexible members flanges are in contact with the outer annular surfaces of these threaded pieces; an arc gear attached to or keyed on the outer surface of each .of said 7 flanges; a hoop-like member rotatable relative to the outer ring; racks on the hoop in mesh with said are gears on the flexible members; radially extending lugs set on the inner ring; holes in collars movably encircling -the inner ring; slots in the collars in which the said pins are engaged; as non-flexible member of appropriate curvature and of stream-dined sectional contour extending radially between the inner and outer rings; a

gear fixed near the inner end bearing of the nonflexible member, meshing with racks cut in edges of the slotted collars; a gear on the outer end of said non-flexible member meshing with a rack attached to the hoop; means for turning the non-flexible member about its longitudinal axis so that the racks on the. hoop actuate the arc gears to change the angular settings of the outer ends of the flexible members while the turning of the collars on the inner ring causes the racks to actuate the inner gears thus changing the angular settings of the inner ends of the flexible members.

17. In a propeller construction, a ring; means capable of causing rotation of the ring; a drive shaft coinciding with the axis about which the ring rotates; a turnable member, non-flexible, stream-lined in section, extending radially between bearings set on the ring and-on the drive shaft; a cowl movable telescopically in relation to the ring; a rack firmly fastened to the cowl; a pinion set on the outer end of said non-flexible memberin mesh with the cowl rack; a gear fastened near the inner end of the non-flexible member adjacent to its drive shaft bearing; a collar surrounding and turnable on the drive shaft; a rack cut in a side of the collar in mesh with said gear; curved slots in the collar; pins engaged in the slots; a ball-bearing having its.

inner race splined with the drive shaft and slidable upon it; fingers attached to and extending outward from a radial surface of said inner race, firmly holding said engaged pins; a rack secured to the outer race of the ball-bearing; brackets on the engine frame or fastened on some solid part of the craft, abutting said rack to prevent rotation of the outer race of the ball-bearing; an arc gear in mesh with the last named rack; a lever integral with said are gear; linkage connecting said lever with one end of an arcuate member, the other end of which swings on a pin fixed conveniently in the pilots cabin or in: the engine room; a setting clamp slidable on saidarcuate member; a pivot pin fixed upon and therefore movable with said setting clamp; a link swinging at one end upon said movable pivot pin; a member, pivotally connected with the other end of this link, having a slldable can place the setting clamp on the arcuate member so that the degree to which relative movements of the cowl and ring afiect the control of the engine may be determined by him.

FREDERICK BUCKIN'GHAM. 

